This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.
Typical of ultrasonic flowmeters that are used in ASME PTC 18 flow measurements (e.g., performance tests for a hydroelectric plant), the plant is “shut down and dewatered” in order to install the ultrasonic transducers (referred to the transducers hereafter) into the flow conduit. The transducers are installed (typically attached to the inside of the conduit/pipe walls or through the conduit/pipe walls) using precise measurements. As such, the line is typically drained, closed and scaffolding is erected such that the transducers can be precisely mounted. Theodolites or other precise measuring equipment are used to make these measurements. The transducers must be well installed, while the measurement may be a one-time event—the installation must be permanent, since the cost of installation and removal is high.
For many hydroelectric plants—particularly those associated with a run of river flow, the ability to “shut down and dewater” the facility is difficult and expensive. The ability to secure a drained conduit/line can in itself be problematic since the cost of such an endeavor in and of itself can overwhelm the value of the measurement.
However, most hydroelectric plants will have gate valve slots (typically there will be two redundant slots) that provide for stop log insertions that are used to isolate the unit for dewatering and maintenance. This is true with most river hydroelectric plants. The present invention takes advantage of these slots.